This invention relates generally to the use of adsorbents to stop bleeding. More particularly, this invention relates to adsorbents incorporated into adsorbent media such as nonwoven materials or films that have improved formulations over the prior art. These formulations contain a sufficient amount of these adsorbents to stop blood loss without containing other ingredients that may counteract the hemostatic function of the adsorbents.
Wounds are generally classified as acute or chronic in accordance with their healing tendencies. Acute wounds from trauma or surgery include wounds such as active bleeding wound sites, e.g., wounds that have detectable, unclotted blood. The rapid control of topical bleeding at active bleeding wound sites is of critical importance in wound management, especially for the management of trauma, e.g., as a result of military exercises or surgery.
Conventional approaches such as manual pressure, cauterization, or sutures may be time consuming and are not always effective in controlling bleeding. Trauma care has received great attention recently as United States troops on a daily basis face combat situations that result in wounds accompanied by significant blood loss. In many cases, the individual may have been able to survive the initial injury only to die of blood loss. Given the central role of hemostasis in trauma care, a great deal of attention has been focused on developing products that can rapidly induce clotting, stop the bleeding, form a tight bond to the wound surface, facilitate scab formation and be compatible with the host tissue. Currently there are several categories of products being used that can be differentiated by their mechanism of action. The first category includes materials that accelerate the coagulation process by absorbing water from the blood. The products in this category include basic cotton gauze. Also within this category are products from Johnson & Johnson's Ethicon division that sells its Surgicel™ regenerated cellulose product line in various forms. There are other cellulosic type products in the marketplace. The second category of products seeks to enhance coagulation by adding features that can increase clotting enzymatic activity. Such products may include such components as thrombin, fibrinogen, propyl gallate, aluminum sulfate, fully acetylated glucosamine and ε-aminocaproic acid. Other hemostatic agents have difficulty adhering to wet tissue and lack a framework onto which a clot can adhere.
Each of these prior art products are deficient in at least one aspect. Products that function solely through absorption of water from the blood tend not to be particularly selective in concentrating the blood constituents useful in clotting such as platelets, erythrocytes and plasmas and therefore are not as effective as other products in enhancing coagulation. The second category of products enhance coagulation by adding components such as thrombin, fibrinogen, propyl gallate, aluminum sulfate, fully acetylated glucosamine and ε-aminocaproic acid that increase clotting enzymatic activity. While these products can be very effective at stopping bleeding they can also be quite expensive, have shelf life limitations and in some cases where the components are derived from animals or humans may offer a mechanism for pathogen transfer or allergic reaction. In the third product category, the HemCon product suffers from potential allergenic side effects, short shelf life and high cost. Some of Z-Medica's QuikClot products suffer from problems with high heat of adsorption that can cause significant discomfort to users and limits its utility in heat sensitive parts of the body. One of the QuikClot products is not optimal since it is literally poured onto the wound and must then be carefully washed from the injury. In addition, it has been found that some formulations of prior art products contain one or more ingredients that have a potentially adverse effect upon the product's overall hemostatic ability and when tested individually may in fact encourage bleeding.
A hemostatic material that is biocompatible, provides superior hemostasis, and that can be fabricated into a variety of forms suitable for use in controlling bleeding from a variety of wounds is still sought. This type of hemostatic material is sought for both surgical applications as well as in field treatment of traumatic injuries. In vascular surgery, due to the involvement of the blood vessels, bleeding is particularly problematic. In cardiac surgery, the multiple vascular anastomoses and cannulation sites, complicated by coagulopathy induced by extracorporeal bypass, can result in bleeding that can only be controlled by topical hemostats. Rapid and effective hemostasis during spinal surgery, where control of osseous, epidural, and/or subdural bleeding or bleeding from the spinal cord is not amenable to sutures or cautery, can minimize the potential for injury to nerve roots and reduce the procedure time. In liver surgery, for example, live donor liver transplant procedures or removal of cancerous tumors, there is a substantial risk of continued bleeding. An effective hemostatic material can significantly enhance patient outcome in such procedures. Even in those situations where bleeding is not massive, an effective hemostatic material can be desirable, for example, in dental procedures such as tooth extractions and other oral surgery, as well as the treatment of abrasions, burns, and the like.
There remains a need for an effective hemostatic product that can be delivered in an easy to use form. Until recently, porous carriers or porous articles, e.g. non-woven fibrous articles containing molecular sieves and hydrophilic oxides had not been disclosed for use as hemostatic devices. Such hemostatic articles comprising molecular sieves have now been found to provide ease of application, effective hemostasis, and reduction in exposure of the patient to high temperature increases owing to high heats of adsorption. These products are also useful in surgical applications that were not available using a powdered molecular sieve or hydrophilic oxide product. The prior art formulations, such as that disclosed in US 2007/0154509, teach the use of two retention aids for reduction of fines loss during the manufacture of the nonwoven materials for use as hemostatic products.